The present invention relates to an ion generating device usable for an electrostatic recording or the like and a method of manufacturing the same.
It is known, as disclosed in U.S. Pat. No. 4,160,257, for example, that ions are generated at a high electric current density and are selectively extracted and applied onto an electrically chargeable member so as to charge the chargeable member (recording medium) with the shape of an image, which is used for an electrotatic printing or the like.
FIG. 1 is a cross-sectional view of a discharging device suitable for use in such a printing process. The device includes a plurality of first electrodes 11, a number of second electrodes 12 and a third electrode 13, arranged as shown in FIG. 1. First electrodes function as inducing electrodes 11 and each extend in a first direction. Second electrodes 12 function as discharging electrodes in the form of finger electrodes and each extend in a direction which is different from the first direction, somewhat perpendicular to the first direction so that a matrix is constituted by those first electrode 11 and second electrodes 12. Third electrode 13 is provided with a number of apertures corresponding to the matrix. First electrodes 11 and second electrodes 12 sandwich a first dielectric member 14. Also, second electrodes 12 and third electrode 13 sandwich a second dielectric member 15. The second dielectric member 15 has a number of apertures 16 corresponding to apertures 17 of third electrode 13. An AC voltage is applied between a selected first electrode 11 and a selected second electrode 12, whereby positive and negative ions are generated adjacent to the second electrode 12 at the cross-overpoint of the matrix determined by selected first electrode 11 and selected second electrode 12. Between second electrode 12 and third electrode 13, a bias voltage is applied so that only the ions that have the polarity determined by the polarity of the bias voltage are extracted out of the positive and negative ions generated. The extracted ions pass through aperture 16 of second dielectric member 15 and through aperture 17 of the third electrode 13 to electrically charge chargeable member (not shown) disposed opposed to the third electrode 13. By selectively driving the first electrodes 11 and second electrodes 12 in the manner described above, a dot-matrix electrostatic recording is performed.
The electrostatic recording using this process is advantageous. However, there is no good method of manufacturing a discharger, particularly for mounting second dielectric member 15 and third electrode 13 after first electrode 11, first dielectric member 14 and second electrodes 12 are assembled into a unit.